JPH0138529B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves adding ammonia gas to the waste gas at a temperature of about 110°C to 180°C, which is formed by a granular carbon-containing adsorbent flowing from the top to the bottom in the reactor. Regarding a method and apparatus for removing sulfur oxides and nitrogen oxides from waste gas by passing it across a fluidized bed, in detail, a part of sulfur oxides from the waste gas is removed using an adsorbent in the first moving bed. The present invention relates to a method and apparatus for removing sulfur oxides and nitrogen oxides from waste gas by separating remaining sulfur oxides in a second moving bed and reducing nitrogen oxides to nitrogen through a catalytic reaction. Such waste gas is generally discharged from the furnace;
Contains oxygen and water vapor. The carbon-containing adsorbent may be used in conjunction with a catalyst or alone. Most of the sulfur oxides present in the waste gas are removed using adsorbents in the first moving bed. Addition of ammonia gas to the waste gas requires that a predetermined amount of ammonia be supplied to the second moving bed, in which nitrogen oxides are reduced to nitrogen through a catalytic reaction.

Among the waste gases discharged from the furnace are sulfur oxides in the form of sulfur dioxide and nitrogen oxides in the form of nitrogen monoxide. A dry one-stage method is known as a method for simultaneously removing sulfur oxides and nitrogen oxides. In this known method, ammonia is bubbled into the waste gas, nitrogen oxides are brought into contact with a porous catalyst and reduced to form nitrogen and water vapor, and sulfur oxides are separated as ammonium sulfate or ammonium hydrogen sulfate.

In the method of using activated carbon as an adsorbent/catalyst, it is known that the temperature is set at 180°C to 230°C (German Published Patent Publication No. 2433076), and
When using a metal oxide supported on aluminum or silicon, the temperature range is 200℃ to 250℃.
It is known to be ℃ (Japan Textile
News 1976, pp. 84-87).

At temperatures below 250°C, both sulfur dioxide and nitrogen oxides react with ammonia; as long as NOx and SO ₂ are present in the same concentration, higher temperatures lead to the reaction of NOx and NH ₃ , and lower temperatures lead to SO ₂ and NH ₃ reaction takes precedence. A disadvantage of these known methods is that the consumption of ammonia is increased, since the ammonia reacts with surface oxides or oxygen. Furthermore, the loss of carbon in activated carbon is generally large.

Furthermore, when the above-mentioned sulfur oxides and nitrogen oxides are simultaneously removed by the above-mentioned general method, the temperature of the waste gas generated in the coal-fired combustion chamber or the oil-fired combustion chamber becomes lower than the reaction temperature required for the above-mentioned simultaneous removal. Since it is about 50° C. lower, it has the disadvantage that the above-mentioned simultaneous removal can only be carried out after the waste gas has been heated by means of an air preheater or an electrofilter. Therefore, either the combustion chamber must be modified to produce a hot waste gas at the expense of its thermal efficiency, or the waste gas must be heated before the sulfur oxides and nitrogen oxides are removed.

The above problems can be significantly improved by carrying out the reaction in a two-step process. That is, in the first stage, for example, sulfur oxides are removed using a moving bed formed by an adsorbent flowing from upward to downward, and then in the second stage, ammonia is removed using a moving bed substantially similar to that in the first stage. In the presence of gas, nitrogen oxides are reduced to nitrogen through a catalytic reaction.

However, in such a method, it is usually necessary to regenerate and supply a large amount of adsorbent per unit time, which not only increases the equipment cost but also increases the amount of adsorbent consumed.

Furthermore, when removing SO ₂ and NOx simultaneously by adding ammonia, limiting the amount of ammonia added and ensuring that the amount of ammonia remaining in the waste gas after treatment does not exceed the allowable value will reduce the removal of SO ₂ . However, regarding NO, the amount of NOx in waste gas is
Only about 50-60% can be removed.

The purpose of the present invention is to improve the removal efficiency of sulfur oxides and nitrogen oxides in conventional methods, reduce the amount of adsorbent circulated to the regeneration process, and reduce the amount of NOx
It is an object of the present invention to provide a method for substantially completely separating SO ₂ while suppressing the ammonia content in the treated waste gas within an allowable range.

It is also an object of the present invention to provide a device suitable for carrying out the above method.

The above purpose is to supply adsorbent to which no adsorbed substance has yet adhered to one or two moving layers, to separate the adsorbent partially adhering to the adsorbed substance from one moving layer, and to separate the adsorbent to which the adsorbed substance is partially attached from one moving bed. The adsorbent is sent to the moving bed, and the adsorbent whose adsorption capacity has decreased due to attachment of the adsorbed substance is separated from the other moving bed and introduced into the regeneration process, and the regenerated adsorbent is sent to the one moving bed again. This can be achieved by a method.

Further, good results can be obtained when the method of the present invention is carried out under the following conditions. In other words, when the adsorbent to which the substance to be adsorbed is partially attached is taken out from one moving bed and sent to the other moving bed, it is not mixed with fresh adsorbent, and the waste gas is first mixed with fresh adsorbent. passing the supplied first moving bed in a specific direction, and then passing the adsorbent partially attached with the adsorbent through a supplied second moving bed in a direction opposite to the specific direction, converting it into nitrogen; Injecting an excess amount of ammonia gas into the waste gas relative to the amount of nitrogen oxides to be produced, and introducing an insufficient amount of ammonia gas into the waste gas before the first moving bed for SO ₂ and NH ₃ to react to form ammonium salts. 2.
It is preferable to add conditions such as making the residence time of the particulate adsorbent in the two moving beds different from each other, and making the residence time of the waste gas in the two moving beds different from each other.

The method of the present invention can also be carried out in other embodiments as follows. That is, the adsorbent to which the substance to be adsorbed is not attached is sent to the second moving bed, and the adsorbent to which the substance to be adsorbed is partially attached in the second moving bed is discharged from the moving bed and transferred to the first moving bed. The adsorbent whose adsorption capacity has been reduced due to adhesion of the adsorbed substance in the first moving bed is introduced from the moving bed into the regeneration process, and the adsorbent regenerated in the regeneration process is sent into the second moving bed again. It is. Incidentally, since the adsorbent to which no adsorbed substance is attached and which is supplied to the second moving bed mainly consists of regenerated adsorbent, the wear of the adsorbent during the circulation process can be compensated for by adding an appropriate amount of fresh adsorbent.

In the above alternative method, the flow rate of the adsorbent suitable for removing sulfur oxides and nitrogen oxides can be adjusted in the second moving bed, and the adsorbent whose adsorption capacity has not decreased is sent to the regeneration step. Not at all. This has a particularly important meaning. This is because if the amount of adsorbent adsorbed in the second moving bed is increased excessively, for example by increasing the residence time,
This is because the purifying effect on sulfur oxides and nitrogen oxides is reduced, and this can be avoided by adjusting the flow rate of the adsorbent in the second moving bed.

Furthermore, although it is disadvantageous that the adsorbent layer through which the waste gas must pass becomes large, in the present invention,
The above-mentioned disadvantages can be overcome by optimizing the flow rate of the adsorbent in the second moving bed and the moving bed thickness for the removal of sulfur oxides and nitrogen oxides. This will not cause an undesirable high load.

Ammonia gas may be added to the waste gas before the first moving bed or before the second moving bed. According to the invention, ammonia gas can also be added to the waste gas before both moving beds. In this way, the removal rate of sulfur oxides and nitrogen oxides in each of the two moving layers can be significantly increased. The addition of ammonia gas before the first mobile bed has a positive influence on the adsorption action of the adsorbent for the removal of sulfur oxides. The addition of ammonia gas only to the second moving bed significantly controls the consumption of ammonia and is particularly effective in removing nitrogen oxides. The addition of ammonia before each of the two moving layers allows very effective control of the reactions that occur in each of the two moving layers.

The method according to the invention opens the door to the efficient reduction of nitrogen oxides at relatively low temperatures in addition to the removal of sulfur oxides, and allows the use of carbon-containing adsorbents in both mobile beds. According to the invention, 20% to 80% of sulfur oxides are removed in the first moving bed. The reduction of nitrogen oxides is approximately
This is carried out using 0.5 to 1.5 mol of ammonia gas.
Regarding the reduction of nitrogen oxides, it is not very important how much nitrogen oxides have already been reduced in the first moving bed and to what position the ammonia gas is supplied.

Ammonia gas may be added uniformly over the entire height of the moving layer, or the amount added may be varied depending on the height position. It can also be added to conduits or conduits leading to individual moving beds. According to the invention, it is particularly advantageous if ammonia gas is forced into the waste gas before the individual moving beds. In other words, it has surprisingly been found that the effectiveness of the process according to the invention is very strongly dependent on the distribution of the ammonia gas into the waste gas stream. This is even more important when ammonia gas is added between both moving layers. In the present invention, ammonia gas is mixed into the waste gas at one or several locations in the flow direction of the waste gas. When adding this ammonia gas, it is particularly effective to mix a very small amount of ammonia gas in the upper part of the flow space formed before the moving bed, and the remaining ammonia gas in the bottom part. This addition method is more effective when ammonia gas is supplied between both moving layers.

The adsorbent that has been separated from the first moving layer and has a reduced adsorption capacity due to the attachment of the adsorbed substance may be regenerated by a known method such as washing or heating.

The two moving beds may have different capacities and may also have different flow rates of adsorbent flowing therethrough. In that case, the adsorbent in the first moving bed is
200 hours, preferably 20 to 150 hours, and in the second moving bed 20 to 300 hours, preferably
It is recommended that the solution be allowed to stay for 20 to 200 hours.

In the present invention, by using 0.05 to 5% by weight of copper, iron, lithium, sodium, aluminum, barium, or vanadium in the form of elements in the carbon-containing adsorbent alone or in combination of multiple types, SO ₂ The removal and NOx reduction can be effectively enhanced.

Removing a portion of the sulfur oxides in the first moving bed can be performed at a higher space velocity than removing all of the sulfur oxides as in the one-step process. Therefore, in the present invention, the waste gas has a space velocity of about 200 to 5000 h ^-1 , preferably 400 to 1800 h ^-1
and is supplied to the first moving bed containing the adsorbent. It is particularly noteworthy that the removal of sulfur oxides is not impaired in any way by feeding the adsorbent, which is already partially loaded with adsorbed substances, into the first mobile bed. In this way, it is possible to maximize the adsorption capacity of the adsorbent in the first moving bed, and the flow rate of the first moving bed can be adjusted to an extremely high level, so that the first moving bed through which the waste gas passes Undesired obstruction of the adsorbent in the moving bed can be avoided.

The process according to the invention surprisingly allows large doses of ammonia to be tolerated and is discharged from the second moving bed together with the treated waste gas. The amount of ammonia is very small. It is therefore possible to dose the waste gas to be treated with an excess amount of ammonia compared to the amount of nitrogen oxides to be converted. Therefore, ammonia is preferably administered in an amount of 1 to 2.5 times the amount of ammonia that is stoichiometrically required for NOx, and more preferably, the amount of ammonia added is 1 to 2.5 times the amount of ammonia that is stoichiometrically required for NOx. Approximately 1.5 of the amount
It is better to double it.

If an insufficient amount of ammonia is added to the waste gas before the first mobile bed for SO ₂ and NH ₃ to react to form ammonia salts, there will be an excess of ammonia relative to the amount of nitrogen oxides to be converted. It has been found to be advantageous that even if ammonia is added, the overall consumption of ammonia is reduced. Therefore, the insufficient amount of ammonia added is in the range of 0.2 to 0.8 times the amount of NH ₃ required for the reaction with SO ₂ , and is particularly preferably about 0.2 times.

Based on the present invention, the residence time of the granular adsorbent in both moving beds is made to be different from each other, which not only affects the amount of adsorbent processed per unit time in the adsorbent regeneration circulation step but also affects the method of the present invention. The optimum composition of the waste gas used and the required removal of SO ₂ and NOx also have an advantageous effect. The residence time of the powder adsorbent in the second moving bed is about 0.5 to 3 times, preferably about 1.5 times, the residence time in the first moving bed. Furthermore, in order to obtain the above-mentioned effects, it is also possible to make the residence times of the waste gas different from each other in both moving beds.

In the present invention, the residence times of the powder adsorbent and waste gas in both moving layers are made different by making the depths (thicknesses) of both moving layers in the flow direction of waste gas different. , or by making the gas flow cross-sections of both moving layers different (this can be adjusted by changing the height or width of the moving layers).

The height, width, and thickness of both moving beds should be selected depending on the characteristics of the adsorbent used, the composition of the waste gas to be purified, the desired degree of purification, etc., and the specific dimensions are determined by the usual professional methods. You can decide based on your knowledge and conduct confirmation tests if necessary. for example,
Waste gas containing SO ₂ 800ppm and NOx 600ppm
Treats 100000m ³ /h and reduces SO ₂ to 98% and NOx to 85%
% If you want to remove both moving layers, the first moving layer should be 12.00m (height) x 7.70m (width) x 1.20m (thickness), and the second moving layer should be 13.00m (height) x 7.70m ( Width)×
It is recommended that the thickness be 1.40m (thickness). Further, the residence time of individual fine particles of adsorbent in the first or second moving bed is about 55 to 66 hours, and the residence time of waste gas is about 4 hours.
It is preferable to set it to 5 seconds.

The apparatus for carrying out the method of the present invention comprises two continuous moving beds formed by powdery adsorbent flowing from above to below, and includes an adsorbent outlet end in one moving bed and an adsorbent outlet end in the other moving bed. is connected to the adsorbent supply end of one of the moving beds through a connecting path that does not include a regenerator, and through this connecting path, the adsorbent with the adsorbed substance partially attached is removed from the one moving bed without being regenerated. It is configured to be supplied to the other moving layer. There are two types of modes in which both moving layers are arranged in series, one of which is where both moving layers are arranged in parallel, and the other is where both moving layers are arranged vertically in series.

In an embodiment in which both moving layers are arranged in parallel, it is preferable to provide a gas-permeable partition between these moving layers, which extends parallel to both moving layers and perpendicular to the flow direction of the waste gas. Furthermore, in one configuration example according to this aspect, the supply port for introducing the adsorbent on which no adsorbed substance is yet attached to the upper end of the second moving bed (the one moving bed) is connected to the first moving bed ( At the lower end of the other moving layer, exhaust ports are provided to take out the adsorbent whose adsorption capacity has decreased due to adsorption of substances to be adsorbed. A drainage conduit and an adsorbent regeneration device are provided. Even if the partition wall in the present invention is provided with only one waste gas passage port, the waste gas moving to the second moving bed can be forcibly mixed well with the ammonia gas. Due to the partition wall having one gas passage port, the waste gas flow path becomes longer than a structure having a plurality of gas passage ports. When the partition wall is provided with only one waste gas passage port, it is preferably provided at a position as low as possible with respect to the effective height of the moving bed. Further, it is preferable that at least one forced mixing device for ammonia and waste gas is provided in this partition wall. Furthermore, in this connection, if a plurality of gas passage openings are provided in the partition, it is particularly advantageous to provide as many forced mixing devices as there are gas passage openings. or,
It may be desirable to add ammonia to the waste gas as far in advance of the second moving bed as possible. In such cases, at least one forced mixing device should be arranged in the flow direction of the waste gas in front of the partition.

On the other hand, in an embodiment in which both moving layers are arranged in series, NOx separation can be further improved.
Generally, as in the present invention, when the waste gas is caused to flow across a moving bed of suspended particulate matter, the suspended particulate matter (in the present invention, the particle adsorbent) The relative positions remain almost unchanged. In other words, as soon as the suspended particles enter the fluidized bed, they are caught up in the nearest flow region, and as long as they remain in the reactor, they remain in the flow region moving perpendicular to the waste gas flow. That is, once the particulates are in the unidirectional flow region, there is little displacement in the direction of the waste gas flow, even if they are subsequently exposed to an orthogonal waste gas flow. Therefore, the state of distribution of fine particles in the upper moving bed is maintained in the lower moving bed, at least with respect to the flow direction of the waste gas. However, for this purpose, it is necessary to ensure that the distribution state of the particulate adsorbent is not destroyed during the transition from the upper fluidized bed to the lower fluidized bed. In addition, in order to effectively utilize such characteristics of the granular adsorbent, it is necessary to make the waste gas flow in a specific direction in the lower moving bed, and then in a direction opposite to the specific direction in the lower moving bed. do. As a result, if the adsorbent flowing from top to bottom in each moving bed is composed of several partial layers that vertically traverse the moving bed, it will come into contact with the waste gas first in the upper moving bed. partial layer (partial layer where most adsorption occurs and the adsorption capacity decreases sharply)
is the last to come into contact with the waste gas in the lower moving bed, which dramatically increases the NOx separation efficiency compared to conventional methods, and at the same time completely and quickly separates SO ₂ . can.

Various types of connecting paths can be used to supply the adsorbent with the adsorbed substance partially attached from the upper moving layer to the lower moving layer. It can be in the form of a connecting chute provided in the middle. still,
The waste gas inflow conduit, the communication passage (for the transfer of waste gas between the upper moving bed and the lower moving bed), the discharge pipe, the ammonia addition device, etc. may be provided by known methods.

It is particularly advantageous for the connecting chute used as the connecting channel to be single and cylindrical. The connecting chute should also be arranged as precisely vertically as possible to reduce adsorbent wear. Furthermore, it is advantageous if the cross-sections of the upper and lower ends of this connecting chute are adapted to the corresponding cross-sections of the upper and lower moving layers. That is, the chute preferably has an upper end that matches the lower end cross-section of the upper fluidized bed, and a lower end that matches the upper end cross-section of the lower fluidized bed. By doing so, not only the horizontal disturbance but also the vertical disturbance of the adsorbent particles can be very significantly prevented, so that the NOx removal efficiency becomes particularly high.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the present invention, in which a reactor 1 is provided with two moving beds 2 and 3 containing a particulate adsorbent flowing from above to below. The waste gas flows across both moving beds. This can be achieved by passing the waste gas through vertically extending gas-permeable walls 4a, 4b, 4c, 4d, for example in the form of slats. The reactor may be provided with a partition wall 5 having a gas passage port 6a extending parallel to both moving layers and located between both moving layers. The partition wall 5
In the example shown in FIG. 1, the gas passage port 6a
at the lower end. Ammonia is added to the waste gas passing through the reactor, but this addition can take place not only before it enters the reactor 1 but also between the two moving beds 2, 3. This ammonia addition can also be performed only in one of the two moving layers. It is preferable that ammonia be added between the two moving layers 2 and 3 by forced mixing. In this case, ammonia gas is added in front of the partition wall 5 in the flow direction of the waste gas. The forced mixing device 6 (see FIG. 2) is particularly suitable for ammonia addition and serves to ensure a good distribution of ammonia gas in the waste gas. As described above, the waste gas is sent into the reactor 1 from the gas introduction pipe 7, flows into the first moving bed 2, then flows into the second moving bed 3 from the lower end of the partition wall 5, and then passes through the gas exhaust pipe 8. It is discharged through chimneys, etc.

A carbon-containing adsorbent such as activated carbon is introduced from the upper end (adsorbent supply end) of the second moving bed 3 through a conduit 9a. Although the adsorbent is introduced in this way, it is simultaneously discharged from the lower end (adsorbent outlet end) of the second moving bed 3, so measuring the falling speed determines the residence time of the adsorbent in the moving bed. . The adsorbent separated from the lower end of the second moving bed 3 is sent to the upper end (adsorbent supply end) of the first moving bed 2 through a connecting path in the form of a conduit 10 . The partially attached adsorbent of the adsorbed substance separated from the second moving layer is transferred to the first moving layer through a conduit 9b connected to the conduit 9a together with fresh adsorbent of the adsorbed substance to which the adsorbed substance is not yet attached. It will be put into 2. Thus, the predetermined flow rate and residence time of the adsorbent in the second moving bed 2 are adjusted by adjusting the discharge rate of the adsorbent to which the adsorbed substance is attached at the lower end of the moving bed 2.

FIG. 2 shows a second embodiment of the device according to the invention. In this embodiment, the ammonia gas is injected into the waste gas stream from several points, in particular in the vicinity of the partition wall 5. In this case, it is preferable that more ammonia gas is introduced at the lower position of the partition wall 5 than at the upper position. In the embodiment shown in FIG. 1, the waste gas flow path in the reactor is longer than that in a structure without partition walls, and the gas flow state in the moving bed may be uneven. In the device of this second embodiment, although the partition wall is provided, the gas flow passage is provided from the upper part to the lower part, so the gas flow passage does not become unduly long, and the gas flow path is not unduly long, and the gas flow path is not unduly long, and the gas flow path is not unduly long. The cross section of the partition wall 5 can be used as an effective gas flow area, and the gas passage port 6a at the bottom of the partition wall 5 contributes to ensuring gas flow to the bottom region where gas flow conditions tend to be poor in the moving layer. . In this way, in cooperation with the ammonia mixing device 6, the ammonia concentration in the waste gas can be made uniform before it flows into the second moving bed 3. Furthermore, the second
In the figure, no adsorbents are shown in both transfer beds 2, 3, in order to clearly represent the flow lines of the waste gas stream passing through the reactor. In addition, in order to effectively utilize the adsorbent that has partially performed an adsorption action as in the first embodiment, the conduit 10 serving as a connecting path connected to the lower end of the second moving layer 3 is connected to the first moving layer. Note that it is connected to the top of 2.

FIG. 3 shows a two-stage moving bed reactor according to a third embodiment of the present invention, where 1' is a first moving bed (upper moving bed) and 2' is a second moving bed (lower moving bed). be. On both sides of both moving layers 1', 2', there are known plate-like interdigital gas permeable walls extending parallel to the flow direction of the waste gas, or gas permeable walls 3a, 3b, 4a, 4 having the same effect.
b is arranged. A suitable adsorbent supply device 5', such as a dual-type opening/closing plate device, is provided above the first moving bed 1', so that the powder adsorbent can be supplied in a controlled manner. On the other hand, a well-known discharge device 6' is provided at the bottom of the second moving bed 2' to take out the adsorbent whose adsorption capacity has deteriorated due to adsorption of substances to be adsorbed. A connecting path 7' provided between the two moving layers 1' and 2' is for transferring the adsorbent on which the adsorbed substance is partially attached from the upper moving layer 1' to the lower moving layer 2'. As this connecting path, for example, as shown in FIG.
A vertically arranged cylindrical connecting chute may be used. The waste gas to be purified is supplied into the first fluidized bed 1' through the waste gas introduction pipe 8', and after crossing the first moving bed, it is fed into the second moving bed 2' through the communication path 9'. After inflowing and crossing this, gas discharge pipe 1
It is discharged from 0'. As is clear from Figure 3,
The flow direction of the waste gas passing through both the upper and lower continuous fluidized beds is completely opposite.

The connecting chute (connecting path) 7' has the same diameter at its upper and lower ends as shown in FIG. 3, and opens in the adsorbent flow direction so as to communicate with both moving beds. The thicknesses (layer thicknesses) of both moving layers 1', 2' are the same in the embodiment of FIG. 3, and differ only in height.

Example 1 In a thermal power plant with an output of 232 MW, the sulfur content was
When bituminous coal containing 1.5% was burned, approx.
Total 750000 containing 660ppm (volume) _SO2
m ³ /h (under standard conditions) of combustion gas was released outside the system. The NOx content in this combustion gas is approximately
Reached 300ppm (volume). 120 in this combustion gas
m ³ /h (under standard conditions) from the waste gas stream as SO ₂ and
In order to remove NOx, it was fed into a two-stage reactor shown in FIG.

The first moving layer used had a thickness (layer thickness) of 1000 mm in the flow direction of waste gas and a cross-sectional area of 192 m ² . The second moving layer used had a layer thickness of 1500 mm and an adsorbent transport capacity of 288 m ³ . Using a moving bed with the dimensions described above, the residence time of the waste gas was 4 seconds in the first moving bed and 6 seconds in the second moving bed. Also, about 4 m ³ of adsorbent was discharged from the lower end of the second moving bed per hour, and the residence time of the adsorbent in the moving bed was 72 hours. Therefore, the moving bed having a height of 19.4 m was sinking at a sinking (flowing) rate of 0.27 m/hour. The adsorbent discharged from the second moving bed was reintroduced from the top of the first moving bed.
Initially, fresh adsorbent was additionally fed into the first fluidized bed at a rate of 2.5 m ³ per hour, and 6.5 m ³ of adsorbent per hour was discharged from the lower end of the first fluidized bed. That is, the residence time of the adsorbent was about 30 hours, and the settling (flow) rate was 0.65 m/hour. The adsorbent discharged from the first moving bed was regenerated in a regeneration step (apparatus) 12 and reintroduced into the system as an adsorbent to which no adsorbed substance was attached.

approximately per hour to compensate for the loss of adsorbent.
0.2 m ³ of adsorbent was introduced into the adsorbent circulation system.

Before the waste gas flows into the reactor 1, about 800 ppm ammonia gas, which is necessary for waste gas treatment, containing 600 ppm SO ₂ , 300 ppm NO 300 ppm and about 6% O ₂ in addition to other normal gases, is added to the waste gas. However, the waste gas discharged from the first moving bed contained SO ₂ 80ppm and
It contained only 200ppm of NO. Furthermore, the partition wall 5
Approximately 350 ppm of ammonia gas was added to the waste gas stream from one point before the test. The waste gas that passed through the second moving bed and reached the gas discharge pipe 8 of the reactor 1 contained virtually no SO ₂ , only 80 ppm of NO, and almost no ammonia.

Example 2 Unlike the case of Example 1, ammonia was not supplied before the first moving bed, and approximately
When 500 ppm of ammonia was supplied, the concentration of SO ₂ in the waste gas immediately after passing through the first moving layer was
The concentration of NO was 120 ppm, and the concentration of NO was 300 ppm, but the measured values of each concentration in the gas discharge pipe 7 of the reactor were as in Example 1.
It was the same as in the case of This shows that the method according to the invention is very flexible.
That is, not only can the total amount of waste gas to be treated be different, but also the concentration of SO ₂ and NOx contained therein and the amount of filler input can be used. If ammonia is mixed into the waste gas in front of the first mobile bed, not only SO will be adsorbed by the adsorbent, but also ammonium sulfate salt will be generated, which will be adsorbed and separated by the adsorbent in the first mobile bed. If the amount of ammonium sulfate salt separated in the first mobile bed is too large, it will interfere with the reaction in the first mobile bed. It should be added constantly before the first mobile bed. Note that the higher the flow rate of the adsorbent in the first moving bed, the greater the amount of ammonium sulfate salt produced.

Regardless of whether ammonia is mixed into the waste gas before the first moving bed or first just before the second moving bed, the concentration of ammonia gas before the second moving bed is calculated as NO. Ammonia should be administered at about 0.4 to 1.5 moles per mole of nitrogen oxide. The amount of ammonia to be administered may be determined by measuring the concentration in the waste gas that has passed through the first moving layer. The amount of ammonia administered also depends on the oxygen concentration in the waste gas.

Although most of the total amount of nitrogen oxides removed from the waste gas by the process of the invention is separated in the second moving bed, only a relatively small amount of SO ₂ is removed in the second moving bed. It should be noted that there is no According to the method of the present invention, nitrogen and water vapor are generated from nitrogen oxides, while SO ₂ is adsorbed on an adsorbent and separated.

In Examples 1 and 2 above, activated carbon (as defined by Brunauer, Emmett and Teller) with a specific surface area of 500 m ² /g was used as the carbon-containing adsorbent. The exhaust gas temperature was 120°C. In addition, by soaking activated carbon in a copper sulfate solution, drying it, and then calcining it at about 500°C, a specific surface area of 470 m ² /g (Brunoyer, Emmett's and Teller's The effectiveness of the present invention was further enhanced when a modified adsorbent was obtained and used.

According to the method of the present invention, the adsorption capacity of the adsorbent can be improved compared to the conventional method without reducing the amount of SO ₂ and NOx separated, without increasing the pressure loss of the exhaust gas, and without increasing the exhaust gas temperature. It is possible to achieve a considerably greater performance, and thereby significantly reduce the burden on the recovery process. What is more important is that the above effects can be obtained even when the required conditions regarding the amount of adsorbent circulated and the amount of ammonia added are different, and the exhaust gas purification effect is good and the adsorbent can be used efficiently. be.

Example 3 Activated carbon (as defined by Brunoyer, Emmett and Teller) prepared for typical waste gas treatment with a specific surface area of 500 m ² /g was used as carbon-containing adsorbent. 1.8 m ³ of adsorbent was used in the first mobile bed. The first moving layer has a cross-sectional area of 2.0 m ² in the flow direction of waste gas, a height of 2.0 m, and a thickness (layer thickness).
We used one with a diameter of 0.9 m. The second moving bed was filled with 1.6 m ³ of activated carbon. Also, as the second moving layer,
The cross-sectional area of waste gas is 2.0m ² and the thickness (layer thickness) is 0.8
m was used.

NOx 0.08 vol%, SO ₂ 0.1 vol%, O ₂ 6.4 vol%
The waste gas discharged from the combustion equipment containing 9.7% by volume of H ₂ O was collected at a rate of 1500 m ³ per hour, a temperature of 120°C, and a space velocity of 800 h ^-1 (calculated value at room temperature). agent) was allowed to pass through the first moving layer. When ammonia was added to this waste gas before the first moving bed, the NH ₃ concentration became 0.02% by volume. In addition, the residence time of activated carbon in the first moving layer is 70
The SO ₂ concentration of the waste gas in hours is 0.018% by volume (desulfurization degree
82%). On the other hand, NOx concentration is 0.07% by volume
decreased to Before sending this waste gas to the second moving bed, a sufficient amount of ammonia gas was added so that the NH concentration in the second moving bed was 0.1% by volume. Then, when the waste gas is passed through the second moving bed at a space velocity of 900h ^-1 (calculated value at room temperature) and a residence time of activated carbon of 62 hours, the SO ₂ concentration becomes 0.003% by volume, and the NOx concentration becomes 0.014% by volume, respectively. decreased. A total of 97%
of SO ₂ and 81% of NOx were removed in both fluidized beds.

In the above description and accompanying drawings, the method and apparatus for removing sulfur oxides and nitrogen oxides in waste gas according to the present invention have been specifically explained based on the examples thereof, but the technical scope of the present invention is The present invention is not limited to the details of the embodiments, and various modifications can be made without departing from the technical idea of the present invention.

[Brief explanation of drawings]

The drawings show an apparatus for carrying out the method of the present invention, and FIG. 1 is a schematic vertical cross-sectional view of the first embodiment, and FIG. 2 is a schematic vertical cross-sectional view of the second embodiment. FIG. 3 is a schematic vertical cross-sectional view of a third embodiment, with only the parts corresponding to the reactor shown in FIG. 3 being shown and other parts omitted. DESCRIPTION OF SYMBOLS 1... Reactor, 2... First moving layer, 3... Second moving layer, 3a, 3b, 4a, 4b, 4c, 4d...
... Gas permeable wall, 5 ... Partition wall, 6 ... Ammonia forced mixing device, 6a ... Gas passage port, 7 ... Waste gas introduction pipe, 8 ... Waste gas discharge pipe, 9a, 9b, 1
1... Conduit, 10... Connecting path (conduit), 12...
Adsorbent regeneration device, 1'...first moving bed (upper moving bed), 2'...second moving bed (lower moving bed), 5'...
Adsorbent supply device, 6'...Adsorbent discharge device, 7'...
...Connection path (connection chute), 8'... Waste gas introduction pipe, 9'... Communication path, 10'... Waste gas discharge pipe.

Claims (1)

[Claims] 1. Adding ammonia gas to waste gas containing sulfur oxides and nitrogen oxides at a temperature of about 110°C to 180°C,
This waste gas is passed through a layer of granular carbon-containing adsorbent flowing from top to bottom in the reactor, and a part of the sulfur oxide is first adsorbed and removed in the first moving bed, and then in the second moving bed. In a method for removing sulfur oxides and nitrogen oxides from waste gas by separating remaining sulfur oxides and reducing nitrogen oxides to nitrogen through a catalytic reaction, the adsorbent to which no adsorbed substance is attached is The adsorbent is fed into one of the two moving beds, the adsorbent to which the substance to be adsorbed is partially adhered is separated from the one moving bed, and the adsorbent is sent to the other moving bed of the two moving beds to absorb the adsorbent. An adsorbent whose adsorption capacity has decreased due to adsorption of adsorbent substances is taken out from the other moving bed and introduced into a regeneration step, and the regenerated adsorbent is sent to the one moving bed. Method of removing sulfur oxides and nitrogen oxides. 2. Feed the adsorbent to which the adsorbed substance is not attached to the second moving layer, take out the adsorbent to which the adsorbed substance is partially attached from the second moving layer and send it to the first moving layer, and remove the adsorbent to which the adsorbed substance is not attached. The adsorbent whose adsorption capacity has decreased due to adhesion of substances is taken out from the first moving bed and introduced into a regeneration step, and the regenerated adsorbent is sent to the second moving bed. The method described in Section 1. 3. The method according to claim 2, characterized in that the adsorbent to which no adsorbed substance is attached is also fed into the first moving layer. 4. A method according to any one of claims 2 to 3, characterized in that the ammonia gas is mixed into the waste gas stream before at least one of the two moving beds. . 5. Process according to any one of claims 2 to 4, characterized in that the ammonia gas is mixed into the waste gas stream before the two moving beds. 6. A method according to any one of claims 2 to 5, characterized in that about 20 to 80% of the sulfur oxides are removed in the first moving bed. 7. Claim 2, characterized in that the second mobile bed is operated in the presence of about 0.4 to 1.5 mol of ammonia gas per 1 mol of nitrogen oxides, calculated as NO, introduced into the second mobile bed. Items to 6th
The method described in any of the paragraphs. 8. The method according to any one of claims 2 to 7, characterized in that the waste gas is introduced into the first moving bed and brought into contact with an adsorbent at a space velocity of about 200 to 5000 h ^-1 . . 9. The method of claim 8, wherein the space velocity is approximately 400 to 1800 h ^-1 . 10 About 0.05 to 5 of one or more of copper, iron, lithium, sodium, aluminum, barium, or vanadium is added to the carbon-containing adsorbent layer.
10. A method according to any one of claims 2 to 9, characterized in that % by weight is added. 11 The residence time of the adsorbent in the first moving bed is approximately
11. A method according to any one of claims 2 to 10, characterized in that the residence time of the adsorbent in the second moving bed is about 20 to 300 hours. 12. The method according to any one of claims 2 to 11, characterized in that ammonia gas is forcibly mixed into the waste gas before the second moving bed. 13. The method according to any one of claims 2 to 12, characterized in that ammonia gas is mixed into the waste gas at one or several locations in the flow direction of the waste gas. 14. The method according to claim 13, wherein a small amount of ammonia is mixed in from the upper part of the waste gas circulation space before the second moving bed, and a large amount of ammonia is mixed in from the lower part. 15 When taking out the adsorbent to which the adsorbed substance is partially attached and sending it to the other moving bed, the adsorbent is not mixed with the adsorbent to which the adsorbed substance is not attached, and The waste gas is passed in a specific direction through a first moving layer in which an adsorbent to which the adsorbed substance is not yet attached is supplied, and then a second moving bed in which an adsorbent to which the adsorbed substance is partially attached is supplied. A method according to claim 1, characterized in that the layer is passed in a direction opposite to said specific direction. 16. Process according to any one of claims 1 to 15, characterized in that a larger amount of ammonia gas is mixed into the waste gas than the amount of nitrogen oxides to be converted. 17. Claim 1, characterized in that an amount of ammonia gas insufficient to react SO ₂ and NH ₃ to form an ammonium salt is mixed into the waste gas before the first moving bed. 17. The method according to any one of Items 1 to 16. 18. The method according to any one of claims 1 to 17, characterized in that the residence times of the particulate adsorbent in the two moving beds are made different from each other. 19. The method according to any one of claims 1 to 18, characterized in that the residence times of the waste gas in the two moving beds are made different from each other. 20 Sulfur oxides and nitrogen oxides in the waste gas are removed by passing the waste gas to be treated sequentially through two continuous moving beds formed by granular adsorbents flowing from above to below. In the removal device, the adsorbent outlet end of one moving bed and the adsorbent supply end of the other moving bed are connected through a connecting path that does not include a regenerator, and the adsorbed substance is partially removed through this connecting path. An apparatus for removing sulfur oxides and nitrogen oxides from waste gas, characterized in that the adsorbent adhering to the waste gas is supplied unregenerated from the one moving bed to the other moving bed. 21 The two moving layers are stacked one above the other in a direction perpendicular to the flow direction of the waste gas, and the adsorbent to which the adsorbent substance has not yet adhered is sent to the upper end, which is the adsorbent supply end, of the upper moving bed. A supply port is provided, and a discharge port is provided at the lower end of the lower moving bed, which is the adsorbent outlet end, for discharging the adsorbent whose adsorption capacity has decreased due to adsorption of substances to be adsorbed. 21. The device according to claim 20, wherein a lower end, which is an agent extraction end, is connected to an upper end, which is an adsorbent supply end, of the lower moving bed. 22. The device according to claim 21, characterized in that the connecting passage is a cylindrical connecting chute. 23. The device according to claim 22, characterized in that the cross-sectional area of the upper and lower ends of the connecting chute corresponds to that of each corresponding moving layer. 24. A claim characterized in that the two moving layers are arranged in parallel, and a gas-permeable partition wall is provided between these moving layers, extending parallel to both moving layers and perpendicular to the flow direction of the waste gas. The device according to item 20. 25. The device according to claim 24, characterized in that the partition wall is provided with a single waste gas passage port. 26. The device according to claim 24, characterized in that the partition wall is provided with at least one forced mixing device for ammonia gas and waste gas. 27. Claim 24, characterized in that, in front of the partition wall, at least one forced mixing device for mixing the waste gas and ammonia gas is provided in the flow direction of the waste gas. The device described. 28. The device according to any one of claims 20 to 27, wherein the two moving layers have different depths (lengths in the gas flow direction). 29 Claim 2, characterized in that the two moving layers have different gas flow cross-sectional areas.
The apparatus according to any one of items 0 to 28.